Diabetes is a major healthcare problem that is reaching crisis proportions, and new therapies are urgently needed. We are developing a long-term glucose sensor with battery-operated telemetry for implantation in subcutaneous tissues. The sensor would have unique applications in type 1 diabetes for hypoglycemia warning, insulin dosing, and control of the artificial pancreas. The sensor may also have application for glucose monitoring in type 2 diabetes, caloric and activity management in obesity, and prevention of type 2 diabetes in susceptible individuals. Development of the long-term implantable glucose sensor has been underway for several years. Previous studies have focused on the development of individual sensor components including: stable preparations of immobilized glucose oxidase and catalase, novel membranes with controlled permeability, electrochemical detectors, implantable electronics and telemetry, signal processing methods, and the hermetic implant housing. Sensors incorporating these components have been tested extensively in vitro and have proven stable. The sensors were tested extensively as short-term implants in rodents to determine the effects of micro-vascular perfusion and mass transfer resistance, leading to minor adjustments in sensor design. In Phase I of this project, the sensor and telemetry system were implanted for 12-18 months in pigs, and results demonstrated that the sensor remains responsive and capable of monitoring blood glucose for extended periods. In addition to the long-term animal performance evaluations, appropriate biocompatibility and other pre- clinical testing has also been completed. In this project, we will now carefully verify that acceptable sensor performance can be obtained in two small-scale pilot human clinical trials, and we will develop patient-friendly instructions for sensor operation, including calibration method and interval. Detailed assessments of sensor accuracy, lag, and sensitivity stability will also be conducted to determine suitability of the device for future use in closed-loop applications. The long-term implantable glucose sensor has an important role in the therapy for diabetes and obesity. The sensor we are developing has undergone systematic engineering analysis, extensive short-term animal tests, and long-term animal implant studies. This project comprises the necessary last steps prior to evaluation of the sensor in large-scale clinical trials. PUBLIC HEALTH RELEVANCE: Diabetes is a major healthcare problem that is reaching crisis proportions, and new therapies are urgently needed. In long-term animal implant tests, we have demonstrated operation of a new glucose sensor that would have unique applications in diabetes for hypoglycemia warning, insulin dosing, and control of the artificial pancreas. In this Phase II project we propose to perform the first human clinical evaluations of the sensor.